The field of the present invention is a one-way clutch, and more particularly a one-way clutch for use in an automotive engine starter.
One-way clutches are widely used in various devices in order to transmit rotative power from one shaft to the other in a prescribed direction, or to allow rotative power to be transmitted from one shaft to the other while the shafts are rotating in one direction and to prevent rotative power from being transmitted from the other shaft to said one shaft.
In automotive engine starters, the rotation of a starter motor is transmitted to a crankshaft, but the rotation of the crankshaft should not be transmitted to the starter motor. To this end, a one-way clutch is disposed between the crankshaft and a driven gear which is rotated by the starter motor.
In a motorcycle, for example, as shown in FIG. 1, a driven gear 04 which can be rotated by a starter motor (not shown) via an intermediate gear 01 is rotatably mounted by a bearing 03 on an end of a crankshaft 02 of an internal combustion engine. The driven gear 04 has a boss 04a over which there is fitted a one-way clutch 010 that is held in position by a rotor 06 of an AC generator 05 on the distal end of the crankshaft 02 and an outer clutch member 08 fixed by bolts 07 to the rotor 06, the rotor 06 and the outer clutch member 08 being collectively referred to herein as the "outer clutch means." The rotation of the starter motor is transmitted via the intermediate gear 01, the driven gear 04, the one-way clutch 010, and the outer clutch means, including rotor 06 and the outer clutch member 08 to the crankshaft 02 for starting the internal combustion engine. When the internal combustion engine is started, the crankshaft 02 is rotated thereby to rotate the rotor 06 and the outer clutch member 08. However, the driven gear 04 is not rotated because of the one-way clutch, and hence the rotation of the internal combustion engine is not transmitted to the starter motor.
FIG. 2 shows the one-way clutch 010 used in the engine starter as described above. The one-way clutch 010 has a number of cams 013 disposed between a pair of ring-shaped side plates 011, 012. The side plates 011, 012 are engaged by a wire cage 015 which alternately engages engaging portions 014 (FIG. 3) projecting in a staggered manner from the inner peripheral edges of the side plates, and the cams 013 are sandwiched and held in position between the side plates 011, 012. A ring-shaped coil spring 018 is wound through grooves 017 defined in the cams 013 and opening outwardly of the one-way clutch for preventing the cams 013 from being dislodged.
In the one-way clutch 010 thus constructed, the inner periphery thereof is fitted over the boss 04a of the driven gear 04, and the outer periphery thereof is retained by the outer clutch member 08. The outer side of the side plate 011 is engaged by the rotor 06 of the AC generator 05 for preventing dislodgement of the clutch.
It is desirable that the one-way clutch 010 thus assembled in position be rotated with the crankshaft 02 by the internal combustion engine, i.e., the outer clutch means, including the rotor 06 of the AC generator 05 and the outer clutch member 08.
To meet the above requirement, the outer peripheral edge of the side plate 011 is bent slightly outwardly into a flange 011a, which is sandwiched between the rotor 06 and the outer clutch member 08 for allowing the side plate 011 to be rotated with the rotor 06 and the outer clutch member 08. However, since the side plate 011 is simply sandwiched between the rotor 06 and the outer clutch member 08, although the side plate 011 tends to rotate with the rotor 06 and the outer clutch member 08, the side plate 011 may rotate more slowly than the rotor 06 and the outer clutch member 08 or may not rotate at all dependent on the friction between these members. If slippage takes place between the rotor 06 and the outer clutch member 08, and the one-way clutch 010, then the portions of the flange 011a and the cams 013 which contact the rotor 06 or the outer clutch member 08 undergo wear.